comparative calorifi c evaluation of biomass fuel … · 2019-01-06 · solid samples of the...

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International Journal of Civil Engineering and Technology (IJCIET)Volume 9, Issue 13, December 2018, pp.

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=13

ISSN Print: 0976-6308 and ISSN Online: 0976

©IAEME Publication

COMPARATIVE CALORIFI

BIOMASS FUEL AND FOS

Mechanical Engineering Department,

Agricultural and Bio-Systems





Chemical Engineering Department,

ABSTRACT

In recent years, fossil fuels have been preferably used

industrial purposes. Fossil fuels are highly flammable and effective but are very

hazardous to the human environment. It is also one of the causes of the ozone layer

depletion which humanity is battling presently. Biomass fuels are ma

waste materials which have good properties that aid combustion, less hazardous and

are effective for some domestic activities and in small

presents the calorific evaluation and analysis of fossil fuel and bio

highlights the effects of fossil fuels in terms of the dangers of increasing CO

concentration in the atmosphere. It presents biomass fuel as a potential substitute for

fossil fuel as a renewable energy by comparing the calorific values

combustible samples such as: rice husk, petrol, diesel, corn cob using a C200 bomb

calorimeter at the Landmark University energy laboratory to determine the calorific

values and to examine if biomass can be used as a suitable replacement for fos

IJCIET/index.asp 1576 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) 2018, pp.1576–1590, Article ID: IJCIET_09_13_15

http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=13

and ISSN Online: 0976-6316

Scopus Indexed

COMPARATIVE CALORIFIC EVALUATION OF

BIOMASS FUEL AND FOSSIL FUEL

C. O. Osueke

Engineering Department, Landmark University, Omu-Aran Kwara State

T. M. A. Olayanju

Systems Engineering Department, Landmark University, Omu

Kwara State

C. A. Ezugwu


A. O. Onokwai


I. Ikpotokin

Engineering Department, Landmark University, Omu-Aran Kwara

D. C. Uguru-Okorie


F.C. Nnaji


In recent years, fossil fuels have been preferably used both for domestic and



depletion which humanity is battling presently. Biomass fuels are majorly agricultural


are effective for some domestic activities and in small-scale industries. This paper

presents the calorific evaluation and analysis of fossil fuel and biomass fuel. It also

highlights the effects of fossil fuels in terms of the dangers of increasing CO


fossil fuel as a renewable energy by comparing the calorific values



values and to examine if biomass can be used as a suitable replacement for fos

[email protected]

IJCIET_09_13_158


C EVALUATION OF

SIL FUEL

Aran Kwara State

Landmark University, Omu-Aran

Aran Kwara State

Aran Kwara State

Aran Kwara State

Aran Kwara State

Aran Kwara State

both for domestic and



jorly agricultural


scale industries. This paper

mass fuel. It also

highlights the effects of fossil fuels in terms of the dangers of increasing CO2


fossil fuel as a renewable energy by comparing the calorific values of various



values and to examine if biomass can be used as a suitable replacement for fossil

C. O. Osueke, T. M. A. Olayanju, C. A. Ezugwu, A. O. Onokwai, I. Ikpotokin, D. C. Uguru-Okorie

and F.C. Nnaji

http://www.iaeme.com/IJCIET/index.asp 1577 [email protected]

fuels. Results show that corn cob has a higher calorific value than rice husk, but both

corn cob and rice husk have sufficient energy to be used as substitutes for petrol and

diesel and other fossil fuels to reduce the dangers of C02 concentration in the

atmosphere and societies over-reliance on fossil fuel.

Keywords: Biomass, Energy, Calorific value, Briquette.

Cite this Article: C. O. Osueke, T. M. A. Olayanju, C. A. Ezugwu, A. O. Onokwai, I.

Ikpotokin, D. C. Uguru-Okorie and F.C. Nnaji, Comparative Calorific Evaluation of

Biomass Fuel and Fossil Fuel, International Journal of Civil Engineering and

Technology (IJCIET) 9(13), 2018, pp. 1576–1590.


1. INTRODUCTION

Energy is vital to human existence. Its application cannot be over emphasis, because its

activities range from and not limited to domestic appliances, transportation, industrial

machines, including sophisticated industrial, and commercial applications, etc. Renewable

energy is a form of energy that comes from resources which are naturally replenished on a

human timescale. It is one of the means of tackling the global challenges of climate change

[1].

Biomass is any organic matter from animals and plants used as energy source, in order

words it has stored energy which can be harvested. When such energy is harvested or

released it is known as biomass energy. In Nigeria wood fuel is used for cooking and in some

areas due to the shortage of wood, dried cow dungs serve as a substitute for wood. The use of

agricultural by-products, wood, and its dust briquetted to generate energy for drying and

cooking has been investigated and found feasible. The use of biomass to produce energy is a

process of recycling waste which might be hazardous to man and the environment or plants

remains after harvest. However, the conversion of raw biomass into source of fuel through

direct combustion is an old method of waste materials utilization, which has led to the

development of gasification and biomass briquette. Biomass briquettes offer a comparative

advantage over the fuel wood, which is not limited to easy of collection, longer burning

interval, higher heating values, lower cost, and reduced environmental impact. [2].

Biomass fuels are different from fossil fuels since fossil fuels are non-renewable energy

which includes but not limited to coal, gas, and gasoline. The burning of fossil fuels by

automobiles and industrial plants have caused air pollution, invariably causing harm to

humans’. Biomass fuels do not release SO2 which are harmful to man [3,4,5]. Owing to the

effects of fossil fuels on climate change and its environmental impact, there is a higher

demand for cleaner and more renewable sources of energy both locally and globally, among

these are energy from sunlight, wind turbines, hydro-powered turbines and biomass; although

not as profoundly tractive as others [6]. Biomass is more practical than all other forms of

renewable energy in most regions of Africa including Nigeria. Its relative availability at low

cost makes it ideal for developing countries, whereas high cost of solar panels, turbines may

pose a constraint to the implementation and development of clean energy.

Briquettes, compressed block of sawdust, rice husk, etc, are important alternative fuel

source for rural dwellers and small-scale industries [7,8]. Other than sawdust, there are

biomasses with high energy potential such as rice and coffee husks, straw, wood chip, and

bark. Forest residues account for 65% of the biomass energy potential and are in abundance in

Nigeria, this can serve as an alternative to fossil fuel in certain sectors, and this can eventually

be used to meet needs [9]. Irrespective of the high generation of agricultural residues, it is

Comparative Calorific Evaluation of Biomass Fuel and Fossil Fuel


what noting that in Nigeria its utilization as fuel is low. This is attributed to sufficient

information concerning biomass fuel utilization technologies [10].

The use of biomass as a biofuel will lead to the reduction of CO2 emissions and Ozone

layer depletion and its palletization has an economic advantage. The pelletizing process will

involve the use of binders such as starch, molasses, heavy oil or phenolic resin [11,12]. Also,

hardeners such as sulphuric acid (H2SO4), potassium hydroxide (H3PO3) and sodium

hydroxide (NaOH) can be added to the biomass materials to improve their mechanical

properties. In the formulation of Biomass feedstock, it consists of, but not limited to glucose

polymers. The Chemical and Physical composition Biomass varies depending on species,

growing conditions, and location.

The intensive growth of emissions from the fossil fuels combustion causes air quality

deterioration. Fossil fuels replacement with biomass can be of fundamental importance for the

protection of public health. The aim of this project is to compare the calorific values of

agricultural wastes (biomass) and fossil fuel and determine if biomass material can be used to

replace fossil fuel.

2. MATERIALS AND METHODS

2.1. Materials

2.1.1. Material Selection

The following criteria were taken into consideration;

• Renewable waste materials.

• Cost of materials.

• Material availability in Landmark University.

2.1.2. Materials utilized

The materials used for the experiment include:

• Corn cobs.

• Rice husks.

• Diesel.

• Petroleum.

2.1.3. Sources of Raw Materials

The Corn cobs and rice husks were obtained from Landmark University Teaching and

Research Farm, Omu-Aran, Kwara State, Nigeria. Materials such as diesel and kerosene were

sourced from a petrol station at Omu-Aran, Kwara state. The preparation and analysis of the

samples were carried out in Landmark University energy research laboratories.

2.1.4. Preparation of the materials

Solid samples of the biomass were milled using an industrial milling machine at the

Landmark University Teaching and Research Farm.


and F.C. Nnaji


Table 1. Calorific Value Analysis

Calorific Value Analysis Gross calorific Value Kj/kg

Diesel 44,800

Petrol 48,000

Corn cobs 12,255

Rice husk 12,005

The calorific values of each biomass and fossil fuel were determined using a bomb

calorimeter that utilizes benzoic acid and is powered by oxygen.

Plate 1. Bomb Calorimeter setup

2.2. Experimental Procedure

2.2.1. Charge Weight Calculation

Before the bomb was opened, we ensured that the samples were weighed and potential

calorific value did not exceed the 7000 cal (2900 Joules) allowable maximum. Which is

designated as;

GCV = ��

�� = 44.8KJ/KG

mf =

��

��.� =0.65g

2.2.2. Procedures for the preparation and charging of fuels

The preparation and charging procedures are fundamentally identical for all fuels. The only

variations are between solid and liquid fuels.

• Preparation of the Water Jacket and Calorimeter Vessel:-The water jacket was filled with

water in advance of testing so that it has time to reach ambient temperature. The calorimeter

vessel locator is at the bottom of the water jacket, which was filled with a measured volume of

(2 litres) water. The calorimeter vessel was then placed inside the water jacket.

• Preparation of Solid Samples: The solid samples were weighed (mf) based on charge weight

calculation and then pelletized, thereafter put into the calorimeter for analysis.



• Preparation of Liquid samples: The liquid samples were weighted in a known crucible weight,

ensuring that the charge weight didn’t exceed the maximum weight calculated in the charge

weight calculation.

• Preparation of the bomb vessel: The bomb vessel was cleaned. Then 55mm nichrome wire

was cut and weighed, and its weight recorded as mw. The wire was slid into bomb electrodes

and tied around the electrodes. The rings on the electrodes were then used to lock the wire so

as to ensure effective electrical contact. Thereafter 100mm Cotton thread was weighed and

recorded as mc, and this was tied to the centre of the wire with some of it dangling. Next was

to load the sample into the crucible holder ring while ensuring the dangling thread came in

contact with the sample (liquid and solid). The top section with the crucible was placed into

the base of bomb calorimeter and firmly locked.

• Oxygen Charging: The bomb was charged with pure oxygen. It was fitted with an oxygen

bottle regulator. Other components like the pressure gauge, safety bursting disc, oxygen bottle

regulator and bomb vessel were connected to each other and the hoses inlets and outlets were

tightened. The pressure regulator knob was turned and the bottle valve opened and the

pressure was recorded. The pressure regulator knob was turned slowly making sure it did not

exceed 25bar. After the recommended pressure was released, the bottle valve and pressure

regulator knob were closed. The hoses were detached from the bomb vessel.

Plate 2. Labtech BL20001 Electronic Compact Scale measuring the mass of Biomass.

Plate 3. Formation of pellet with the press.


and F.C. Nnaji


Plate 4. Bomb Electrode slots to accept the use of screw nicrochrome wire.

2.2.3. Conducting A Calorimetric Test

The bomb was charged with the correct weight of fuel and the vessels pressurized with pure

oxygen to a maximum of 25bar, thereafter the bomb vessel was placed inside the calorimeter

vessel filled with 2 litres of water. The ignition terminals, temperature sensor and the stirrer

were connected and positioned properly. The stirrer and the sensor were in contact with the

water inside the calorimeter vessel. The other end of the ignition cables were connected to the

corresponding bomb ignition sockets at the rear of the control console.

The procedure was to monitor the temperature at 1-minute intervals until there is no

change.

Once the rising temperature was stable, the time of the last reading was recorded and the

bomb firing button was pressed. We continued monitoring and recording the temperature

every minute. The initial rise in temperature was rapid, but slowed down and continued for a

while after firing. The rise in temperature is considered to have reached maximum

temperature once the temperature rise starts to progressively fall or remain constant for

typically 5 successive minute readings.

Plate 5. Bomb Vessel Plate 6. Bomb vessel placed inside calorimeter vessel



3. RESULTS AND DISCUSSION

This aspect of the work analyses and discusses the various experiments and results obtained.

3.1. Bomb calibration procedure

When the bomb was charged with fuel and oxygen and ignited, it heats the sample, however,

the heat generated also heats the mass of water of known weight in the calorimeter vessel and

the heavy stainless steel bomb vessel. Therefore to account for the heat gained by the bomb

material a calibration was done using benzoic acid of calorific value of 6319 cal/g (or 26450

J/g).

Since the mass of water in the calorimeter vessel was kept constant, so the effective heat

equivalent ɛ generated was calculated as:

ɛ = [mbax qvba +Ԛfuse + Ԛign] / θ (3.1)

Where,

Mba = benzoic acid (g)

qvba = gross calorific value of benzoic acid (J/g)

Ԛfuse = heat attributed to the cotton thread (J)

Ԛign = heat attributed to the nichrome ignition wire (J)

θ = corrected temperature rise of the calorimeter vessel (K)

3.1.1. Procedure

• A pellet of Benzoic acid was prepared with a weight of 1g, then the solid sample testing

procedure was followed.

The weight (mba) of benzoic acid = 0.981 g

• The bomb was prepared for firing with the pellet following stated testing procedures.

mw, mass of nichrome wire = 0.005g

mc, mass of cotton thread = 0.010g

• The bomb was charged with oxygen.

• A calorimetric test was carried out and data was recorded.

• Sample data is shown below:

mc, Mass of cotton thread = 0.010g


mba, mass of benzoic acid = 0.981g

Mass of water in calorimetric vessel = 2kg

Mass of wire left after firing = 0.0g

Initial water temperature = 18.2°C

Cotton fuse is assumed to have a calorific value of qc = 4180 cal/g (17496.6 J/g)

Nichrome wire is assumed to have a heating effect of qw = 0.335 x 10-3

cal/g (1402.2 J/g)

Temperature rise data for Benzoic Acid can be seen from the figure below, the maximum

temperature rise θ = 2.33K.


and F.C. Nnaji


Figure 1. Temperature rise with respect to time for Benzoic Acid

3.1.2. Sample Calculations

For the cotton thread

Ԛfuse = mc x qc (3.2)

= 0.010 x 17496.6

= 174.966 J

Qign = mw x qw (3.3)

= 0.005 x 1402.2

= 7.011 J

For the bomb,

ɛ =�� Ԛ��Ԛ��

� (3.4)

=�.��∗��.��.��

�.��

= 11214.346 J/K

This is the constant value for the bomb assuming no components are changed and the

mass of water in the calorimeter vessel remains 2kg. The factor ɛ is used in subsequent

calorimetric calculations as follows.

3.2. Fuel Testing

Having calibrated the bomb, the procedure for testing fuel and calibration is almost identical.

3.2.1. Diesel Test

In this case, the fuel being tested is diesel.

• The charge (liquid charge) was prepared following the procedure of testing for calorific value

of liquid samples and the weight was recorded.

From u

mf, mass of diesel = 0.585g

• We prepared the bomb for firing with the liquid fuel following the stated procedure.





• The bomb was charged.

• A calorimetric test was carried out

The data is shown below;



mf, mass of diesel = 0.585g

mass of water in calorimeter vessel = 2kg

mass of wire after firing = 0.0g

initial water temperature = 19.0°C



cal/g (1402.2 J/g)

Temperature rise data for Diesel Sample can be seen from the figure below. The

maximum temperature rise θ = 0.01-0.55 = 0.54K

Figure 2. Temperature rise with respect to time for Diesel Sample

The gross calorific value of the sample qvf can be calculated from.

Qvf = �ɛ�� !��!��

�� (3.5)

where;

mf = fuel sample (g)

qvf = calorific value of benzoic acid (J/g)

Qfuse = heat contributed from the cotton thread (J)

Qign = heat contributed from the nichrome ignition wire (J)

θ = temperature rise of the calorimeter vessel (K)

Sample calculation


Ԛfuse = mc x qc

= 0.085 x 17496.6

= 1487.2 J

Qign = mw x qw


and F.C. Nnaji


= 0.040 x 1402.2

= 56.1 J

For the bomb,

ɛd = 11214.34 J/K

For the diesel sample,

qvf = �ɛ�� !�� !��

��

= ��.��.�� .�� .�

�.�� = 7713.56 J/g

3.2.2. Petrol Test



mf, mass of petrol = 0.30g




bottle pressure gauge = 80bar

outlet pressure gauge = 24.5 bar



cal/g (1402.2 J/g)

Temperature rise data for Petrol Sample can be seen from the figure below. The maximum

temperature rise θ = 0.26-0.07 = 0.19K.

Figure 3. Temperature rise with respect to time for Petrol Sample

Qvf = �ɛ�� !�� !��

��

mf = fuel sample (g)

qvf = calorific value of benzoic acid (J/g)

Qfuse = heat contributed from the cotton thread (J)

Qign = heat contributed from the nichrome ignition wire (J)

Sample calculation




Ԛfuse = mc x qc

= 0.010 x 17496.6

= 175.0 J

Qign = mw x qw

= 0.005 x 1402.2

= 7.01 J

For the bomb,

ɛp = 11214.34 J/K

For the diesel sample,

qvf = �ɛ�� !�� !��

��

= ��.��.�� .��

�.��

= 6500 J/g

3.2.3. Rice husk Test



mf, mass of rice husk = 1.20g








cal/g (1402.2 J/g)



cal/g (1402.2 J/g)

Temperature rise data for Rice husk Sample can be seen from the figure below. The

maximum temperature rise θ = 0.46-0.12= 0.34K.

Figure 4. Temperature rise with respect to time for Benzoic Acid


and F.C. Nnaji


Sample calculation


Ԛfuse = mc x qc

= 0.010 x 17496.6

= 175.0 J

Qign = mw x qw

= 0.005 x 1402.2

= 7.01 J

For the bomb,

ɛrh = 11214.34 J/K

For the rice husk sample,

qvf = �ɛ�� !�� !��

��

= ��.��.�� .��

�.�

qvf = 3035 J/g.

3.2.4. Corn cob Test



mf, mass of maize cob = 1.22g








cal/g (1402.2 J/g)

Temperature rise data for Corn cob Sample can be seen from the figure below. The

maximum temperature rise θ =0.62-0.19 =0.43 K.

Figure 5. Temperature rise with respect to time for Corn Cob Sample



Sample calculation


Ԛfuse = mc x qc

= 0.010 x 17496.6

= 175.0 J

Qign = mw x qw

= 0.005 x 1402.2

= 7.01 J

For the bomb,

ɛcc = 11214.34 J/K

For the maize cob sample,

qvf = �ɛ�� !��!��

��

= ��.��.�� .��

�.��

qvf = 3850 J/g

Table 2 Physical and Chemical Composition of Rice husk and Maize cobs. Agbongiarhuoyi, A.

(2015).

SAMPLE UNITS RICE HUSK MAIZE COB

CARBON % 20.93 19.73

HYDROGEN % 17.22 15.00

SULPHUR % 3.82 4.48

MOISTURE CONTENT % 48.51 42.98

GROSS CALORIFIC VALUE J/g 12300 12255

NET CALORIFIC VALUE J/g 3035 3850

Figure. 6. Comparative analysis of diesel and petrol


and F.C. Nnaji


Figure. 7. Comparative analysis of rice husk and corn cob

3.3. Discussion

The graphs above show that the temperature of the combustible matter increases with respect

to time. Figure 6 shows that petrol is more combustible than diesel fuel. Figure 7 indicates

that corn cob has a higher calorific value than rice husk which means that corn cob is more

combustible than rice husk and is a viable substitute for fossil fuels. The petrol combust faster

than diesel while diesel burns at a higher temperature.

4. CONCLUSION

A sustainable energy source was produced by pelletizing rice and corn cobs into strong pellet

fuel without a binder. The pellets have lightweight (1-2g), genuinely solid and can withstand

compressive drive of no less than 800N, this ensures easy of transportation. The gross

calorific values of these fuels; rice husk, corn cob, diesel, and gasoline have been determined

experimentally with the C200 bomb calorimeter. The project showed that corn cob has a

higher calorific value than rice husk which means that corn cob is more combustible than rice

husk and is a viable substitute for fossil fuels. The petrol combust faster than diesel while

diesel burns at a higher temperature.

RECOMMENDATION

The project has established that pellet fuel can be produced from corn cobs and rice husk

without the addition of binder. However further research can be on the design of portable

pellet machine and pellet stove.

ACKNOWLEDGMENTS

Authors are grateful to the management of Landmark University for all their effort towards

the achievement of this research. We are also grateful to the laboratory staff and students of

the university who played different roles in this work.



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